Create custom CSB image repository

Also sort alphabetically and add trailing comma to facilitate sorting

Related to:

cloud-gov/csb#1
cloud-gov/product#2943

terraform/stacks/ecr/stack.tf

@@ -12,19 +12,20 @@ variable "repositories" {
     "cloud-service-broker",
     "concourse-task",
     "cron-resource",
+    "csb",
     "email-resource",
     "general-task",
     "git-resource",
     "github-pr-resource",
     "harden-concourse-task",
     "harden-concourse-task-staging",
-    "playwright-python",
     "harden-s3-resource-simple",
     "harden-s3-resource-simple-staging",
     "pages-dind-v25",
     "pages-node-v20",
-    "pages-python-v3.11",
     "pages-playwright-v1",
+    "pages-python-v3.11",
+    "playwright-python",
     "registry-image-resource",
     "s3-resource",
     "s3-resource-simple",
@@ -33,7 +34,7 @@ variable "repositories" {
     "slack-notification-resource",
     "sql-clients",
     "time-resource",
-    "ubuntu-hardened"
+    "ubuntu-hardened",
   ]
 }